Circuit breaker



May 31, 1955 E. J. WALKER ET AL CIRCUIT BREAKER Filed July 15. 1950 5| ON OFF 04? 35 O gf g O .1 a4 7% 55 33 27 39 n 3 H 34 a K57 g! 9 s9 s3 73 WITNESSES: I INVENTORS V]! 6 Eugene J. Walker and.

Francis L. Gelzheiser nited. state 3 2,709,729 CIRCUIT BREAKER Eugene J. Walker, Beaver, and Francis L. Gelzlrciser,

Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Appiication July 15, 1959, Serial No. 174,066 14 Claims. (Cl. 200-88) Another object of the invention is to provide a circuit breaker embodying an improved operating mechanism that is manually operable to open and close the breaker and that is adapted to be tripped in response to predetermined overload conditions to cause automatic opening of the breaker.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional obiects and advantages thereof, will be best understood from the following detailed description when read in conjunction with the accompanying drawing.

in said drawing:

Figure l is a side eievational View, with the cover broken away and partly in section, of a circuit breaker embodying the principles of the invention.

Fig. 2 is a view similar to Fig. l but illustrating a modification of the invention.

Referring to Fig. 1 of the drawing, the circuit breaker comprises generally a housing 11 and a cover plate 13 (shown broken away) constructed of molded insulating material, stationary contact means 15, movable contact means 17, an operating mechanism ii and a trip device 21.

The stationary contact 15 is rigidly secured to the inner end of a multi-angular terminal member 23 which is seated in an angular slot 25' formed in the housing 11. The outer end of the terminal 23 is provided with a connecting means 27 for connecting the terminal 23 in an electric circuit. At the opposite end of the housing 1i 4 is a terminal which, at its inner end, supports the electromagnetic portion of the trip device 21 and which is provided with a connector 31 at its outer end for connecting the terminal in an electric circuit.

The movable contact 7 is rigidly secured to the free end of a U-shaped switch arm 37 having its legs 57 supported in recesses in the inner ends of the legs 55 of a U-shaped operating lever constructed of molded insulating material. The operating lever 35 is provided with trunnions 47 molded integral therewith which are pivotally mounted in companion openings in the housing 11 and the cover i3. An overcenter operating spring 39 is connected under tension between the bight of the switch arm 37 and a releasable carrier 33. The carrier 33 is formed from a fiat strip of bimetal and has a bearing member 34 welded to one end thereof and pivotally mounted on a pin 4-1 supported in companion openings in the housing 11 and the cover plate 13. The carrier 33 is normally releasably restrained in operative position by means of an adjusting screw 63 in the free end of the carrier 33 engaging a pivoted latch 65 pivoted on a pin 67 mounted in companion openings in the housing 11 and the cover 13. A spring 6% normally biases the latch 65 to latching position.

The operating lever 35 is provided with a handle or finger piece 49 molded integral therewith which extends through an opening 51 in the housing 11. The operating lever 35 is also provided with an arcuate member 53 molded integral therewitn cooperating with the housing 11 to substantially close the opening 51 in all positions of the handle 49. The switch arm 37 is electrically connected by means of a flexible connection 59 to the bimetallic carrier 33 at a point intermediate the ends thereof as shown, and the free end of the bimetallic carrier 33 is electrically connected by means of a flexible connection 6%) to the inner end of the terminal 29, thus connecting the right-hand portion of the bimetallic carrier to be traversed by the current of the circuit.

The switch arm 37 is operated to manually open and close the contacts by manipulation of the handle 4-9. Movement of the handle 4? and the operating lever 35 in a clockwise direction carries the legs 57 of the switch arm 37 across to the left of the line of action of the overcenter spring 39 which then biases the switch arm 37 to the open position and causes movement of the switch arm to the open position with a snap action.

The contacts are manually closed by reverse movement of the handle 4-9. counterclockwise movement of the handle 49 from the open position moves the legs 57 of the switch arm 37 across to the right of the line of action of the spring 39 which thereupon acts to close the contacts with a snap action.

The circuit breaker is adapted to be tripped open instantaneously in response to overload currents above a predetermined value, or in response to short circuit currents, and after a time delay in response to lesser overload currents by means of the trip device 21. Operation of the trip device 21 releases the carrier 33 whereupon the overcenter spring 59 moves the carrier 33 clockwise, moving the line of action of the spring 39 over to the right or" the center line of the switch arm 37. Thereafter the spring 39 acts to move the switch arm to open position with a snap action. The movement of the carrier 33 is arrested by engagement with a projection 61 of the housing 11.

The trip device 21 comprises the bimetallic carrier 33 connected by means of the flexible conductor 59 to the switch arm 37' and by means of the flexible conductor to the terminal 29, an electromagnet including a channel-shaped magnet yoke "it. rigidly secured to the terminal 29 and an armature 73 secured to the pivoted latch member 65. That portion of the bimetallic carrier 33 (Fig. l) to the right of the point of attachment of the flexible conductor 59 thereto is disposed to be heated by the current of the circuit. The high expansion side of the bimetallic carrier 33 is disposed on the outside and when heated a predetermined amount in response to overload currents below a predetermined value of, for instance, 1000% of normal rated current, the free end of the carrier 33 deflects toward the left releasing the adjusting screw 63 from the latch member 65. Upon release or" the carrier 33 the overcenter spring 39 actuates the mechanism to efiect opening of the contacts in the previously described manner.

The breaker is tripped open instantaneously in response to overload currents above the predetermined value, or in response to short circuit currents, by the electromagnet 71-73. Upon the occurrence of such an overload current, the electromagnet is energized by the current llowing through the terminal 29 sufficiently to attract the armature 73 and actuate the latch member to effect instantaneous release of the carrier and opening of the contacts.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving the handle 49 clockwise to the full open position during which movement the legs 55 of the operating lever 35 engage a pin 84 welded to the carrier 33 and move the carrier counterclockwise about its pivot 41. Near the end of its counterclockwise movement, the free end of the carrier wipes by the latch member 65 which is immediatetly snapped to latching position beneath the screw 63 by the spring 69. Thereafter the switch arm 37 is moved to close the contacts i517 in the previously described manner by movement of the handle 49 counterclockwise to the closed position.

According to the modification of the invention illustrated in Figure 2, the releasable carrier is only partly composed of bimetal. The other parts of the Fig. 2 modification are the same as shown in Fig. l and have been given the same reference numerals.

The releasable member of the Fig. 2 modification comprises a pivoted rigid member 75' mounted on the pivot pin 41 and having a bimetal element 77 rigidly secured thereto by welding or by means of a rivet 79 as shown. The adjusting screw 63 carried by the free end of the bimetal element 77 engages the latch member 65 in the same manner as in Fig. l. The flexible conductor 59 is electrically connected to the bimetal element '77, preferably by welding, at a point adjacent the point at which the bimetal element is attached to the member 75. The flexible conductor 6i connects the free end of the bimetal element 77 to the inner end of the terminal 29.

The operation of the Fig. 2 modification is essentially the same as that previously described for Fig. 1. Upon the occurrence of an overload current below the predetermined value, the bimetal element deflects toward the left and releases the carrier 75'77 whereupon the overcenter spring 3? actuates the carrier to effect automatic opening of the contacts. When an overload current above the predetermined value or a short circuit current occurs, the tripping electromagnet is energized and actuates the latch member 65 to substantially release the carrier 7577 and effect instantaneous opening of the contacts. The circuit breaker is reset and the contacts closed following an automatic opening operation in the previously described manner.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising relatively movable contact means, a movable switch member carrying said movable contact means, a current-carrying releasable member formed froma strip of bimetalelectrically connected in series relation with said contact means and heated in response to the current of the circuit, said releasable member flexing when heated a predetermined amount in a direction to release itself and effect automatic opening of said contact means, an overcenter spring connected between said releasable bimetallic member and said switch member operable upon release of said releasable member to move said switch member to open said contact means, and electro-responsive means having an armature normally restraining said releasable member and operable in response to excessive overload currents to effect instantaneous release of said releasable member.

2. A circuit breaker comprisin relatively movable contact means, a movable contact member for opening and closing said' contact means, a current-carrying releasable member formed from a strip of bimetal having a portion electrically connected in series relation with said contact means to be heated in response to the current of the circuit, latch means on said releasable member, a pivoted latch engaging and normally restraining said latch means to releasably restrain said releasable member in operative position, said releasable member when heated a predetermined amount in response to overload currents below a predetermined value flexing in, a direction to release itself and effect automatic opening of said contact means, an overcenter spring connected between said releasable bimetallic member and said switch member operable upon release of said releasable member to move said switch member to open said contact means, and electroresponsive means operable in response to overload currents above said predetermined value to actuate said pivoted latch and eriect instantaneous release of said releasable member.

3. A circuit breaker comprising relatively movable contacts, a movable current-carrying switch arm having one of said contacts secured thereon, an operating lever operatively supporting one end of said switch arm, a current-carrying releasable member formed from a strip of bimetal, said releasable member being electrically connected in series relation with said contacts to beheated in response to the current of the circuit, an overcenter spring having one end attached to said bimetallic releasable member and the other end attached to said switch arm, said overcenter spring being operable upon release of said bimetallic releasable member to move said switch arm to open said contact means, said bimetallic releasable member flexing when heated a predetermined amount in a direction to release itself and effect automatic opening of said contacts.

4. A circuit breaker comprising relatively movable contacts, a movable current-carrying switch arm having one of said contacts secured thereon, an operating lever operatively supporting one end of said switch arm, a current-carrying releasable member formed from a strip of bimetal, said releasable member being electrically connected in series relation with said contacts to be heated in response to the current of the circuit, an overcenter spring having one end attached to said bimetallic releasable member and the other end attached to said switch arm, said overcenter spring being operable upon release of said bimetallic releasable member to move said switch arm to open said contact means, said bimetallic releasable member flexing when heated a predetermined amount in a direction to release itself and elfect automatic opening of said contacts, and electromagnetic means having an armature releasably restraining said bimetallic releasable member and operable to instantaneously release said bimetallic releasable member.

5. A circuit breaker comprising relatively movable contacts, switch member movable to open and close said contact means, a releasable bimetallic member electrically connected in series relation with said contacts to be heated by the current of the circuit, said bimetallic releasable member when heated a predetermined amount flexing in a direction to release itself and effect automatic opening of said contacts, an overcenter spring connected between said releasable bimetallic member and said switch member operable upon release of said releasable member to move said switch member to open said contact means, and an electromagnet including an armature normally restraining said bimetallic releasable member in operative position and operable to release said bimetallic member to eifect instantaneous opening of said contacts.

6. A circuit breaker comprising relatively movable contacts, a switch member movable to open and close said contact means, a releasable member having a portion composed of bimetallic material electrically connected in series relation with said contacts to be heated by the current of the circuit, latch means normally engaging said bimetallic portion to releasably restrain said releasable rnember in operative position, said bimetallic portion of saidreleasable member'when heated a predetermined amount flexing in a direction to release said releasable member and effect automatic opening of said contacts, an overcenter spring connected between said releasable bimetallic member and said switch member operable upon release of said releasable member to move said switch member to open said contact means, and electroresponsive means operable to actuate said latch means to release said releasable member and effect instantaneous opening of said contacts.

7. A circuit breaker comprising relatively movable contacts, a movable current-carrying switch arm having one of said contacts secured thereon, an operating lever operatively supporting one end of said switch arm, a releasable bimetallic member electrically connected in series relation with said contacts to be heated by the current of the circuit, an overcenter spring having one end connected to said bimetallic member and the other end connected to said switch arm, said releasable bimetallic member when heated a predetermined amount flexing in a direction to release itself, and said releasable bimetallic member when released changing the line of action of said overcenter spring to effect automatic opening of said contacts.

8. A circuit breaker comprising relatively movable contacts, a movable current-carrying switch arm having one of said contacts secured thereon, an operating lever operatively supporting one end of said switch arm, a releasable bimetallic member electrically connected in series relation with said contacts to be heated by the current of the circuit, an overcenter spring having one end connected to said bimetallic member and the other end connected to said switch arm, said releasable bimetallic member when heated a predetermined amount flexing in a direction to release itself, and said releasable bimetallic member when released changing the line of action of said overcenter spring to effect automatic opening of said contacts, and an electromagnet having an armature releasably restraining said bimetallic releasable member and operable to eflect instantaneous release of said releasable bimetallic member.

9. A circuit breaker comprising relatively movable contacts, a movable current-carrying switch arm having one of said contacts secured thereon, terminal means for connecting said breaker in an electric circuit, a releasable bimetallic member, a first flexible conductor connecting said releasable bimetallic member to said terminal means, a second flexible conductor connecting said releasable bimetallic member at a point spaced from said first flexible conductor to said movable switch arm so that a portion of said releasable bimetallic member is traversed by the current of the circuit, an overcenter spring having one end connected to said bimetallic member and the other end connected to said movable switch arm, said releasable bimetallic member being heated by the current of the circuit and when heated a predetermined amount flexing in a direction to release itself, and said releasable bimetal-' lic member when released changing the line of action of said overcenter spring to effect automatic opening of said contacts.

10. A circuit breaker comprising relatively movable contacts, a movable current-carrying switch arm having one of said contacts secured thereon, terminal means for connecting said breaker in an electric circuit, a releasable bimetallic member, latch means normally restraining said releasable bimetallic member in operative position, a first flexible conductor connecting said releasable bimetallic member to said terminal means, a second flexible conductor connecting said releasable bimetallic member at a point spaced from said first flexible conductor to said movable switch arm so that a portion of said releasable bimetallic member is traversed by the current of the circuit, an overcenter spring having one end connected to said bimetallic member and the other end connected to said movable switch arm, said releasable bimetallic member being heated bythe current of the circuit and when heated a predetermined amount in response to overload currents below a predetermined value flexing in a direction to release itself from said latch means, and

said releasable bimetallic member when released changing the line of action of said overcenter spring to eflect automatic opening of said contacts, and electroresponsive means operable in response to overload currents above said predetermined value to actuate said latch means and effect instantaneous opening of said contacts.

11. A circuit breaker comprising relatively movable contacts, a pivotally supported bimetallic member releasable to effect automatic opening of said contacts, electromagnetic means having an armature pivotally supported on a fixed pivot, said armature normally engaging and releasably restraining said bimetallic releasable member, thermal bending of said bimetallic releasable member when heated in response to certain overload current releasing said bimetallic releasable member from said armature to effect automatic opening of said circuit breaker, and said electromagnetic means being operable in response to certain other overload currents to actuate said armature and instantaneously release said bimetalic releasable member.

12. A circuit breaker comprising relatively movable contacts, a bimetallic member pivoted at one end and releasable to effect automatic opening of said contacts, an electromagnet having an armature pivoted on a fixed pivot and normally engaging the other end of said bimetallic releasable member to releasably restrain said member in operative position, said pivoted bimetallic releasable member deflecting when heated in response to certain overload currents in a direction to release itself from said armature, and said electromagnet being operable in response to certain other overloads to actuate said armature and instantaneously release said bimetallic releasable member.

13. A circuit breaker having relatively movable contacts, operating means for said contacts comprising a pivoted releasable member formed at least in part from a strip of bimetal and movable when released to cause automatic opening of said contacts, an electromagnet having an armature pivoted on a fixed pivot and engaging said bimetal to releasably restrain said releasable member in operative position, the bimetal part of said releasable member being disposed to be heated by the current of the circuit and deflecting when heated a predetermined amount in response to certain overload currents to release said releasable member from said armature, and said electromagnet being operable in response to certain overload currents to disengage said armature from said bimetal to effect instantaneous opening of said contacts.

14. A circuit breaker having relatively movable contacts, a releasable member pivoted at one end and having a portion thereof formed of a strip of bimetal disposed to be heated by the current through the breaker, said releasable member being movable when released to eifect automatic opening or" said contacts, electroresponsive means including an armature pivotally supported on a fixed pivot, said armature normally engaging the bimetallic portion of said releasable member to releasably restrain said releasable member in operative position, thermal bending of said bimetal portion of said releasable member when heated in response to certain overload currents effecting release of said releasable member from said armature, and said electroresponsive means being operable in response to certain other overload currents to actuate said armature and release said releasable member.

References Cited in the file of this patent UNITED STATES PATENTS 1,437,617 Radley Dec. 5, 1922 2,182,864 Frank Dec. 12, 1939 2,190,517 Jennings Feb. 13, 1940 2,203,462 Frank June 4, 1940 2,229,412 Jennings Jan. 21, 1941 2,325,717 Swingle Aug. 3, 1943 2,370,340 Wood Feb. 27, 1945 2,573,307 Casey Oct. 30, 1951 

